三种杀虫剂对麦田蚜虫和捕食性天敌群落的影响

以2种选择性杀虫剂吡虫啉、抗蚜威和一种广谱性杀虫剂氧化乐果为试验材料，研究了选择性杀虫剂对麦田蚜虫和捕食性天敌群落结构特征的影响。结果表明，施用选择性杀虫剂的小区在农药持效期内麦蚜群落的多样性指数和均匀度低于空白对照区，高于氧化乐果处理区，而优势度和优势集中度高于空白对照区，低于氧化乐果处理区；捕食性天敌群落的多样性指数低于空白对照区，高于氧化乐果处理区，优势度和优势集中度高于空白对照区，低于氧化乐果处理区。选择性杀虫剂处理区瓢蚜比小于空白对照区和氧化乐果处理区，且有效期长达15－16d。根据害虫和天敌发生的特点及选择性杀虫剂的特性，提出了麦蚜的有效防治措施，即在麦蚜为害关键时期，每667m^2用吡虫啉1g(ai)或抗蚜威2.5g(ai)喷施1次，再利用自然天敌调控作用，即可有效控制麦蚜。

Impacts of three insecticides on the community structures wheat aphids and their predators in wheat field

The characteristics of community structures of wheat aphids and their predators in wheat fields after treated with pirimicarb, imidacloprid, and omethoate were analysed and compared. The results showed that the diversity indexes and evenness of wheat aphid and predator communities of both pirimicarb and imidacloprid treatments were lower than those in non-spraying plots and higher than those in omethoate treatment; while the dominance and dominant concentrations of the former two treatments were higher than those in non-spraying plots and lower than those in omethoate treatment. In a rather long period (15 - 16 days) , the ratio of ladybird to aphids was the lowest in pirimicarb and imidacloprid treatments. Based on the results mentioned above, the effective management strategies against wheat aphids were proposed as to spray only one time of 2.5 g pirimicarb WP (ai)/667m2 or 1.0 g imidacloprid WP (ai)/667m2 in early milking stage of wheat, the critical damage period of wheat aphids, and then to rely on the suppression of natural enemies without insecticide spraying for keeping the aphid population under control.